This invention relates to water-based liquid foam extinguishing formulations. There are three groups of extinguishing formulations. They include the universally usable extinguishing powders which normally contain monoammonium phosphate and ammonium sulfate as their extinguishing agents, which are projected with CO2 as propellent gas. Disadvantages of extinguishing powders are the residues left after the extinguishing process and the emission of dust into the environment.
The second group of extinguishing formulations includes the so-called halons where halogenated hydrocarbons act as extinguishing agents. The halogenated hydrocarbons evaporate completely, but are no longer acceptable on account of the threat they pose to the environment.
The third group comprises extinguishing liquids. This group includes foams based on fluorine surfactants which are also known as lightwater foams or AFFFs (aqueous film-forming foams). Foams such as these are unstable and flowable and spread very quickly over surfaces on which they form a covering film layer. They cover the surface of a burning liquid, for example burning petrol, very quickly. The fluorine surfactants have a very low surface tension (15 to 18 mN/m) and provide the foam with the ability to wet surfaces very thoroughly. However, since they are low foamers and form unstable foams, fluorine surfactants are combined with a co-surfactant in order to obtain a certain degree of foaming and stability of the foam formed. Foams of this type are described in EP 0 300 070 B1 and in EP 0 676 220 A1.
However, fluorine surfactants have the undesirable property that, after dissolution in water, they separate in the event of storage of the extinguishing formulation, thus making it unstable. In order to overcome this problem, therefore, it is known that the extinguishing formulation can be initially introduced in the form of two different components which are only mixed immediately before discharge of the extinguishing formulation from a fire extinguisher. However, this is complicated and requires a special design of the fire extinguisher itself.
The problem addressed by the present invention was to provide a water-based liquid foam extinguishing formulation which would be present in a stable, storable and ready-to-use form. The extinguishing agent would be suitable both for fire class A (glowing solids) and for fire class B (liquid combustible materials and those which become liquid) according to DIN EN 2. In addition, it would be frostproof and both storable and usable over a broad temperature range.